Methods for controlling the fill volume of crane grapples are known. In such methods, adjustment/control electronics interact in a crane's movement cycle to optimize the movement cycle with respect to specified parameters. For example, via interaction of adjustment/control electronics in the movement cycle, an increase in travel and thereby the best possible utilization of the crane will be achieved during its operation.
Methods are also known which, by corresponding interactions in the crane's movement cycle, will achieve protection of the crane by avoiding overloading of the crane. Here, the static equilibrium of the crane in particular is protected with regard to adjustment/control engineering, in which taking up too great a load is at first detected and then prevented. Also, such methods may be used in operator-assisted systems, in which, depending on the method, simplification of crane handling will be achieved, for instance.
At the same time, it is problematic that many influencing factors determine the degree to which the grapple is filled. These factors may include both the angle of grapple entry into the material to be loaded and the compactness of the material, which can vary by more than 20% within a load on a ship to be unloaded, for example. The grapple geometry, or the oblique traction operating on the grapple, may also play a role. Because overloading the grapple can lead to crane damage, the crane controller or operator prefers to partially fill the grapple clearly less than is in fact allowed or would be possible.
The task of the present disclosure is therefore to make a method available for controlling the fill volume of a grapple, by means of which improved filling of the grapple is achieved.
This problem is solved according to the present disclosure by a method for controlling the fill volume of a grapple, in particular a bulk-material grapple of a crane, wherein the grapple includes at least one hoist-and-closure unit and wherein the fill volume of the grapple is adjusted during the process of closing the grapple by adjusting/controlling the grapple hoist height, in which the grapple hoist speed and/or the grapple hoist height is the controlling parameter.
In this way, it is possible for the controller or operator to predetermine the closure speed of the grapple, and the system, being based on a model, optimizes the required hoist height of the grapple during the closure process, with the effect that the desired degree of fill is achieved.
The process of filling the grapple is thereby partially automated, which makes it easier for the controller to achieve optimized grapple-fill status without the fill process being beyond the ultimate control of the controller. Possible overloading of the crane structure is therewith concomitantly reduced and is avoided in the optimum case. Also, any possible negative effect of the operator on the fill volume is minimized. Consequently, less experienced operators can clearly increase the travel, or conversely the energy expended by the operator can generally be clearly reduced.
To carry out the method according to the present disclosure, an adjustment/control device is coupled to the crane or can be provided on the crane in the conventional manner, said device being designed for this purpose to record sensor input or sensor values, to process, and to emit an adjustment/control signal on the crane or crane unit.
In one embodiment, it is conceivable that, depending on the sensor values measured, a necessary temporary change in the grapple hoist height is continuously determined using a model, in order to achieve the target load to be lifted by the crane.
At the same time, the model can advantageously react dynamically to changing parameters in a crane-assembly run, such as, for example, changing material compactness in the material to be loaded or other changing parameters, and they are optimized in reference to the crane or to existing requirements. Consequently a self-teaching system is made available, which can adjust dynamically to different situations.
In another embodiment, it is conceivable that additionally or alternatively, depending on the grapple closure speed, a necessary temporary change in the grapple hoist height is continuously determined using a model, in order to achieve the target load to be lifted by the crane.
The method can thus use as an input parameter, for example, the grapple closure speed defined or definable by a controller as an input parameter and, depending on the grapple closure speed, can adjust grapple hoist speed so that the required or desired target load of the grapple is achieved during the grapple-fill process. The model used can at the same time be designed so that it has recourse to both the grapple closure speed and further sensor values.
In another embodiment, it is conceivable that the grapple closure speed can be controlled by the control crew of the crane. It is thereby advantageously made possible for the control crew or controller of the crane to supply the input grapple closure speed for the method according to the present disclosure, through corresponding control signals or input values, input by said personnel by means of an input console, for example.
In another embodiment, it is conceivable that during the operation of the crane, parameters of the model are continuously optimized, depending on deviation from the target, in which said target deviation is the deviation between the target load to be lifted and the load actually being lifted.
As a result, the method automatically examines the effectiveness of its model and can accordingly adjust the parameters of the model in running operation so that deviation between the load actually being lifted and the desired or specified target load is minimized.
In a further embodiment, it is conceivable that further sensor inputs or sensor values are recorded by means of the model, such as the weight of the grapple and/or the angle of entry into the material and/or the depth of material penetration.
Because of this, it advantageously makes it possible to increase the precision of the model and therewith the effectiveness of crane operation. In principle, however, additional sensors are not required, and the method, in contrast to existing cranes, can be used with the sensors provided on said crane in the conventional manner.
Further details and advantages of the present disclosure are now explained using the figures.